Share time

[Sandy Johnston]

Share time

I have stumbled across a wee 'tove worth its weight in gold.

1 x low voltage motor
1 x electonic speed control
1 x reverse switch.

All wrapped up in a varispeed cordless drill I was trashing cause
the el-cheapo battery pac died.
New 9.7V battery $NZ 70+
or new 12 VDrill $NZ 30 complete

By carefully dismantling the trigger and removing the return
spring and reassembly, it would be suitable for servo control.
Capacitors needed on the motor.

And all I was after was a small key less chuck - what a bonus.

Ekelfekin
AK NZ

[Paulrjordan]

Hi Sandy:

Thank you for an interesting post. Do you have any way of putting an
ammeter on the motor and checking the draw? The advantage of these
cordless drill motors is they have lots of torque but I have always
found them to be a little heavy on juice. Maybe you could also
specify the make and model of the old cordless drill (if you didnt
junk the shell yet!). The "speed controller" you refer to is, I
imagine, a pressure (finger) operated control?

Thanks again for posting this info

Regards

PJ
Victoria, British Columbia, Canada

[Sandy Johnston]

Hi there,
I have finally got my hands on my testing equipment and will try
to get some measurements this weekend.

I am using a Tamiya 7.2V motor in an RC off road buggy as I
want the to utilise the diff in a sidepaddler car ferry.
I am using 7.2v nicad, and seem to get 50% more time at lesser
rpm.

The speed controller is a finger trigger type with variable speed.
The cordless drill was a 14 V Taiwan import through "Dick Smith
Electronics" (self branded) - an electrical hobby shop here like
"Tandy"

The only downside I have found is there is a hi pitch "whistle"
just before the motor actually spins but that may go when I put in
some .1MFcapacitors across the motor connections.

The ideal would be a separate battery for power and another for
radio/servos

Regards
Ekelfekin
AK NZ

[Sandy Johnston]

In my testing the motor was driving a differential and two tyred
wheels through “worn rubber bearings” the rpm at the
wheels is
far too high for what I intend I will have to slow final drive down
to
an acceptable rate but that is another project

Using a 9.2V motor not a 7.2V as previously stated, battery is
9.2V 900mA I came up with the following:-
"Full power" through the speed controller -
fully charged battery - 9.3 V 2.6A
Stall 3 seconds everything held stopped and full power applied -
2.3 15.2A - (motor slightly hot)

Through the speed range:-
Volts then Amps
2.5 1
3.4 1.2
3.7 1.3
4.0 1.4
4.3 1.5
5.0 1.7
6 0 1.9
Jump to:-
8.9 2.4
9.3 2.6

Run time -
full power 13 minutes
half power 23 minutes stopped then full power applied for
another 2 minutes..

The Speed controller produces a soft high pitch whistle at the
motor just before the motor shaft starts to rotate even with
capacitors connected - this is not a problem for me but is a bit
unusual.

I hope this helps you.

Regards
Ekelfekin
AK NZ